These are the Connections I am using on the I/O Bus.
The Scart Connector Pins
+==============================+ | 1 3 5 7 9 11 13 15 17 19|(21) - - shield | \ | 2 4 6 8 10 12 14 16 18 20 | +================================+
Bus Connections & LED I/O Line Use.
| 1 LED3 I2C SDA
3 LED5 I2C SCL 5 LED7 7 LED9 9 LED11 LCD RS 11 0v 13 0v 15 +3v 17 +5v 19 Serial TX |
2 LED 4 LCD D4
4 LED6 LCD D5 6 LED8 LCD D6 8 LED10 LCD D7 10 LED12 LCD E 12 0v 14 +3v 16 +5v 18 Reset Input 20 Serial RX |
I added extra power lines as the wire used is quite fine. The extra power and 0v lines are connected at the router, they are not linked on the Bus I/O board to avoid any ground loop.